Solar One is the first widely recognized house to use photovoltaic panels to generate electricity while also using solar energy for heating. The University of Delaware completed and dedicated the two-bedroom experimental house in 1973.
| Milestone | Date | What happened |
|---|---|---|
| Early solar-heated house | 1939 to 1940 | MIT developed an experimental house heated by sunlight. Sources differ slightly depending on whether they use the completion or occupancy date. |
| Dover Sun House | 1948 | Maria Telkes and architect Eleanor Raymond created a solar-heated home in Dover, Massachusetts. It used solar collectors and Glauber's salt to store heat. |
| Practical silicon solar cell | 1954 | Bell Labs developed the first practical silicon photovoltaic cell capable of producing useful electricity. |
| First major photovoltaic house | 1973 | The University of Delaware dedicated Solar One, which converted sunlight into both electricity and heat. |
| Solar panels on the White House | 1979 | Jimmy Carter installed solar thermal panels to heat water. They were not photovoltaic panels for household electricity. |
What Was the First House With Photovoltaic Solar Panels?
Solar One at the University of Delaware is the strongest documented answer. The house used thin-film photovoltaic modules to generate electricity and solar thermal equipment to provide heat.
The University of Delaware describes Solar One as the first house to convert sunlight directly into both heat and electricity for domestic use. Its system was experimental. Commercial residential solar panels were not yet common, so researchers and students built many of the components themselves.
When Did Solar Heating First Appear in Houses?
Solar heating appeared in experimental houses in the late 1930s and 1940s. These systems used sunlight for space heating rather than generating electricity.
MIT's early Solar House projects used sunlight to heat homes. The Dover Sun House, built in Massachusetts in 1948, became one of the best-known examples. It used large solar collectors and Glauber's salt for thermal storage, allowing the building to stay warm without a conventional furnace.
Why Did Rooftop Solar Take So Long to Become Common?
Rooftop solar took decades to spread because early photovoltaic cells were expensive and inefficient. Before residential systems became practical, solar cells were used mainly in specialized settings such as satellites and remote equipment.
The 1973 oil crisis increased interest in solar power for homes, but residential systems remained costly for many years. Rooftop solar became more common later as panel prices fell and installation methods improved.
The short version is:
- Solar heating appeared in experimental houses from about 1939 to 1948.
- Bell Labs developed a practical silicon solar cell in 1954.
- The University of Delaware completed Solar One in 1973, the first widely recognized house to combine photovoltaic electricity with solar heating.
- Residential rooftop solar became widespread much later.